If 31z5 is a multiple of 3 where z is a digit what might be the value of z.

Given: If 31z5 is a multiple of 3 where z is a digit

To Find; The value of z so the whole number is divisible by 3

Solution:

31z5   is  multiple of   '3'

  divisibility rule of 3 :

Sum of digits must be divisible by 3

$3 + 1 + z + 5$

put  $z  =  0$

$3 + 1 + 0 + 5  =  9$     [9 is multiple of 3]

put  $z  =  3$

$3 + 1 + 3 + 5  =  12$     [12 is multiple of 3]

put  $z  =  6$

$3 + 1 + 6 + 5  =  15$     [15 is multiple of 3]

put  $z  =  9$

$3 + 1 + 9 + 5  =  18$     [18 is multiple of 3]

 So, z can be  0 , 3 , 6 , 9

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Updated on: 10-Oct-2022

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